Heating device



HEATING DEVI CE Filed April 24, 1947 3 sheets sheet l April 1950 H. c. HEBARD 2,503,201

HEATING DEVICE Filed April 24, 1947 3 Sheets-Sheet 3 Inventor 19060 (Aw/945.: HEB/9R0 A E/VT Patented Apr. 4, 1950 UNITED STATES PATENT OFFICE HEATING DEVICE Application April 24, 1947, Serial No. 743,499 In Great Britain May 13, I946 13 Claims. 1

This invention relates to electrical heating devices and radiators and has for its object to provide improved forms thereof wherein one concentrated heat source at high temperature can be utilised to heat a larger area uniformly at a lower temperature.

According to the invention an electrical heatin device comprises a heating element capable of being heated to a high temperature arranged between two: or more components of" high conductivity and of greater area than the heating element and sheets of heat insulating material disposed closely adjacent each of said conductive components each insulating sheet being of smaller area than the adjacent conductive component.

According to one 'form of the invention an electric radiator comprises a number of metal sheets of different areas. assembled in close parallel relationship, sheets of" heat insulating material disposed between adjacent metal sheets, each insulating sheet being of smaller areathan the adjacent metal sheet, and an electrical h'e'ating element disposed between two" metal sheets of the assembly.

Reference will now be made to the accompany ing drawings which show examples of constructions according tothe invention and in which:

Fig. 1 is'an elevation of an electricradiator,

Fig. 2 is a cross-sectional elevation taken on line AB of Fig. l,

Fig, 3 is a perspective view of the radiator shown in Figs. 1 and 2,

Fig. 4 is a sectional elevation of a modified form of radiator, and

Fig. 5 is a sectional view of'a plate foruse in an electric oven construction.

Referring first to Figures 1-3, the radiator illustrated comprises two plates l and 2 of slightly curved form constructed of light sheet metal of high thermal conductivity such as aluminium, secured to base members or feet 3, side members d'and a front casing 5, also of sheet metal. The upper edge of the casing 5 is connected by struts 6 with the upper part of the back plate 2 whose side edges are formed with rearwardly extending flanges l.

The electrical heating element 8 isdisposed substantially centrally of and between the back plates l and 2 and at the rear of the plate I isan asbestos sheet 9 coinciding in position and area with the heating element, the asbestosslieet being backed by a plate ID of metal such asirom To accommodate theseplates the'rear plate I is formed or provided.- with a. casing H The position of the heating elementll'is shown by broken lines in Fig l which also indicates its relatively small area as compared with the area of the back plates. It is capable of sustaining a'temperature up toas much as 900 centigrader At the back of plate I is an asbestos sheet 12. Disposed in front of the back plates is a metal plate I3 which is of substantially smaller area than the back plates which are separated from the plate l3 by an asbestos sheet M which is of slightly less area than the plate [3. In front ofthe plate 13 is another metalsheet l5 of still smaller area which is separated from the-plate Why a sheet I6 of asbestos.

In the operation" of the arrangement above described, the heating'element 8 causesthemetal plates I and 2 to become hot.- The'radiation of heatfrom plate I is reduced by the heat insulat ingmaterial l2 and tromplate' 2 by the heat insulating material l4. The'bo'rderportion of plate 2 which surrounds-the edges of insulating sheet l4 thereby becomes hotter than it would do were the-insulating sheet not present and consequently radiates more heat to the surrounding atmos phere; The metalplate I3 is heated by gradual conduction ofheat from plate 2 through the insulating material I4 Owing to the position of the insulating sheet l6,- theplate l3 is caused co-radiate" more heat from its portions surrounding the sheet [6 and the central metal plate 15 is'heated by slow conduction of heat through-the insulating sheet l6. By these means the concentrated heat source I constituted by the element 8' whose temperature may reach as high as 900 centigrade is made to produce a substantially uniform, although lower. temperature, over the whole front surface of the heater.

Figure 4 showsanother form of radiator similar to that illustrated in Figures 1-3, but in which the he'at radiation takes place equally from both sides. The heating element H in this construction' is disposed betweentwo parallel metal sheets I8, on the outer'surfac'es of which are disposed insulating sheets I! of smaller area than the sheets I'8. On the outer sides-of the insulating sheets are further'metal sheets" 20; which in turn carry on their outer surfaces insulating sheets 2 I, covered by metal sheets 22. Theradiator is maintained with the metal and asbestos sheets in avertical position by supporting the larger metal sheets lfi'irom' a base 23'. Iii-both forms of the invention shown in-Figures l'-3 en"d 4, the radiator is not limitedto -tlieexact'number of metal sheets illustrated; as this can be varied to suit conditions.

sheet 29 designed to reduce radiation from the centre of the metal sheet 21. The inside wall of the oven may conveniently be formed by a continuous metal sheet 3t having good contact with metal sheets 28 and 2'! whereby the sheet 30 is substantially uniformly heated over its entire surface.

The unit illustrated in Fig. 5 is designed to serve either as a base or as a side component for an electric oven. This form of construction is particularly advantageous because it provides even heating throughout an oven and greatly facilitates cleaning of the interior of the oven.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed frontmarginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a flat high-temperature electrical heating unit back of and having a vertical heating surface closely-adjacent the'rear-most and largest one of said metal sheets.

. 2.A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent ,each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a fiat high-temperature electrical heatingunit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, said heating unit having a vertical heating surface area, substantially less than the front and smallest one of said metal sheets. i

3. A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other andincluding alternate conductive sheets of metal-havinghigh heat conductivity and intermediate heat insulating sheets -of ma-,

terial having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a flat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, said sheets and said heating unit having substantially the same form and being substantially centered relatively to each other.

4. A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets havin a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a fiat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, said heating unit having a vertical'heating surface area substantially less than the front and smallest one of said metal sheets, said sheets and said heating unit having substantiallythe same form and being substantially centered relatively to each other.

5 A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheetshaving exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a fiat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, said sheets and said heating unit having rectangular forms and being substantially centered'relatively to each other.

6. A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having loW heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an, area slightly .less than the area of said metalsheet next in front of it, and a flat high-temperature electrical heating unit back of and having a vertical heati surface closely adjacent the rear-most and largest one of said metal sheets, said sheets and said heating unit having rectangular forms and being substantially centered relatively to each other, said heating unit having a vertical heating surface area substantially less than the front and smallest one of said metal sheets.

7. A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of materialha'ving low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the'marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, a flat high temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, and an additional sheet of heat insulating material back of and closely adjacent the rearmost and largest one of said metal sheets and retarding radiation rearwardly from said rearmost metal sheet.

.8. A radiator for space heating air by radiation, including in combination'a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a fiat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, the rear-most of said metal sheets comprising two similar and spaced thicknesses of sheet metal closely adjacent the front and rear heating surfaces of said heating unit and containing said heating unit between them.

9. A radiator for space heating air by radiation, including in combination a plurality of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, and a flat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, the rear-most of said metal sheets comprising two similar and spaced thicknesses of sheet metal closely adjacent the front and rear heating surfaces ofsaid heating unit and containing said heating unit between them, and an additional sheet of heat insulating material back of and closely adjacent the rear-most and largest one of said metal sheets and retarding radiation rearwardly from said rear-most metal sheet.

10. A radiator for space heating air by radiation, including in combination a first set of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heatinsulating sheets having an area slightly less than the area of said metal sheet next in front of it, a flat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, and a second set of sheets similar to said first set of sheets and similarly related to each other, said heating unit having a second and rear vertical heating surface closely adjacent the largest and rearmost metal sheet of said second set, whereby heat is radiated to the air in opposite directions from both sides of said radiator.

11. A radiator for space heating air by radiation, including in combination a first set of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, a flat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, and a second set of sheets similar to said first set of sheets and similarly related to each other, said heating unit having a second and rear vertical heating surface closely adjacent the largest and rear-most metal sheet of said second set, whereby heat is radiated to the air in opposite directions from both sides of said radiator, said sheets and said heating unit having substantially the same form and being substantially centered relatively to each other.

12. A radiator for space heating air by radiation, including in combination a first set of respectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of material having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the heat metal sheet back of it, each of said heat insulating sheets having an area slightly less than the area of said metal sheet next in front of it, a

fiat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, and a second set of sheets similar to said first set of sheets and similarly related to each other, said heating unit having a second and rear vertical heating surface closely adjacent the largest and rear-most metal sheet of said second set, whereby heat is radiated to the air in opposite directions from both sides of said radiator, said sheets and said heatin unit having substantially the same form and being substantially centered relatively to each other, said vertical heating surfaces of said heat- :ing unit being each of substantially less area than the outer-most and smallest one of the metal sheets of the adjacent set of sheets.

13. A radiator for space heating air by radiation, including in combination a first set of re- Spectively continuous and vertically disposed parallel sheets of material held closely adjacent each other and including alternate conductive sheets of metal having high heat conductivity and intermediate heat insulating sheets of matetial having low heat conductivity, said metal sheets having exposed front marginal surfaces for heat radiation, each of said metal sheets having a substantially smaller area than and leaving exposed the marginal radiating surface of the next metal sheet back of it, each of said heat insulating sheets having an area slightly less than the 8 area of said metalsheet next in front o'fit, afiat high-temperature electrical heating unit back of and having a vertical heating surface closely adjacent the rear-most and largest one of said metal sheets, and a second set of sheets similar to said first set of-sheets and similarly related to each other, said heating unit having a second and rear vertical heating surface closely adjacent the largest and rear-most metal sheet of said second set, whereby heat is radiated to the air in opposite directions from both sides of said radiator, said sheets of each of said set of sheets having similar rectangular forms and a substantially centered relation to each other, and said heating unit having rectangular front and back heating surfaces closely adjacent and substantially centered relatively to said sets of sheets respectively.

HUGH CHARLES HEBARD.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

